1. Field of the Invention
The present invention relates to a flowmeter sensor for measuring the flow of a gas or other fluid used in the manufacture of semiconductors.
2. Description of the Related Art
A conventional flowmeter sensor includes a conduit (sensor tube) through which a fluid flows, and a temperature-sensitive resistance wire wound on the outer periphery of the sensor tube as exemplified in U.S. Pat. No. 4,815,280.
In the prior art flowmeter sensor, the sensor tube has quite a small diameter, approximately 1 mm, and the temperature-sensitive resistance wire has a diameter of approximately 0.02 mm. As such, it is cumbersome to wind the temperature-sensitive resistance wire on the sensor tube. It is also cumbersome to adjust the resistance value of a heater/resistor since it is determined by the number of turns of the heat-sensitive resistance wire. Another problem with the prior art flowmeter sensor is that the resistance wire is loosened when the heater/resistor is heated at a high temperature for a substantial length of time. This results in a change in the resistance value of the heater/resistor.